I see 3 problems.

Combination starting-deep cycle batteries are sort of like all season
tires. They try to be all things but they are a compromise at best.

Many deep cycle batteries are made from modified starting batteries. The
quality for the demand is not there. Rolls-Surrette and Trojan are the
brands you want. The Trojan is affordable.

Battery charging. Relying on an engine alternator will properly charge a
deep cycle battery. Economy trickle chargers do not help.

For large engine starting and occasional deep cycle use, try this.
http://www.trojan-battery.com/Products/Commercial.aspx

Here is the list of their marine products.
http://www.trojan-battery.com/Products/Marine.aspx
The T-105 is probably the standard for a reasonable deep cycle battery
that lasts. My previous motor home had a set of these from the factory.
At 5 years and 64,000 miles of RV use, they were still going strong at
trade in. The new RV uses 4 of these to support the 2,500 watt inverter.

Proper charging requires use of an intelligent, 3 stage charger.
http://www.trojan-battery.com/Tech-Support/BatteryMaintenance/ChargerSel
ection.aspx

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Robert Cardo
Sent: Saturday, August 20, 2005 11:52 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: optima the one for starting battery?

Flame on Dennis.

I want to empty your head of the knowledge you have on this.

I have been using deep cycle batteries for 30 some years in my boats.
Maybe max 2 years if I yanked them out of the hull and kept the on a
trickle charger all winter.

(900 or 1000 cca batteries marine deep cycle batteries ain't cheap .
And I think that is because it sez marine on them )

Ok Dennis, unload on me.

Why aren't the gel cell batteries any better than the sulfuric acid and
lead plate batteries???

I need to know prior to taking the plunge.

Thanks,